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Equiaxial nano-crystals Nb3Al superconductor prepared by optimized mechanically alloying
- Zhang, Wenjie, Li, Pingyuan, Zou, Xiaofeng, Yu, Zhou, Yang, Xinsheng, Pan, Xifeng, Zhao, Yong, Zhang, Yong
- Journal of materials science 2019 v.54 no.6 pp. 5022-5031
- chemical composition, magnetic fields, microstructure, milling, nanocrystals, superconductivity, temperature
- The influence of the original nominal chemical composition, milling time, sintering temperature and holding time was studied systematically on the phase formation, microstructure and superconductivity of mechanically alloyed Nb₃Al. By optimizing the process, we have successfully prepared high-performance Nb₃Al superconductor. Samples with original nominal composition of Nb-27 at.%Al were milled for 3 h and sintered at 900 °C for 1 h, resulting in an entire A15 superconducting phase, except a few negligible Nb₂Al phase. The superconducting critical transition temperature (Tc) and the upper critical field at absolute zero (Hc₂(0)) reached 15.7 K and 28.1 T, respectively. It should be noted that the superconducting critical current density (Jc) was still as high as 6.3 × 10⁴ A cm⁻² at a temperature of 4.2 K under an applied magnetic field of 7 T, as well as a maximum flux pinning force (Fₚ,ₘₐₓ) of 6.23 × 10⁹ N m⁻³ in the whole magnetic field range at 4.2 K. All of the results could be attributed to the microstructure of the sample with equiaxial nano-crystals.